Why race cars have stationary spoilers?

I frequently hear something like "......this car have stationary spoiler like race cars" bla bla. Why are stationary spoilers used in motorsports? Active spoilers are very useful for breaking and accelerating. I want to know the reason behind it.

Staff: Mentor

I frequently hear something like "......this car have stationary spoiler like race cars" bla bla. Why are stationary spoilers used in motorsports? Active spoilers are very useful for breaking and accelerating. I want to know the reason behind it.

Thanks.

You want to achieve maximal traction by minimal resistance and friction. Spoilers normally increase the pressure towards the road to increase traction and have a design that helps to avoid air resistance, esp. vortices. Take formula one cars for example. Nowadays their design is that of an airplane which is pressed on the track by aerodynamic design including spoilers of which some cannot be seen from above or from far.

Are you using the word 'spoilers' specifically or aerodynamic devices generically? Wings, etc. One reason is that regs from the relevant sanctioning bodies often rule out active aerodynamic devices. Other cases aerodynamic devices are specified by regs or vehicle homologation. I suspect failure of the active device could be an issue as well. Youtube have quite a few videos of sudden mechanical of wings. I recall the skirts of the ground-effect era F1 cars were banned due to the danger resulting from loss of downforce when the skirts lost contact with the track such as when bouncing over kerbs. Failure of an active spoiler in cornering with loss of the assisted braking and downforce could be catastrophic if it takes a driver by surprise.

The rear spoilers can be used to reduce drag by setting the flow separation further back on the body. At the same time, it helps increasing stability by setting rearward the center of pressure further away from the center of gravity. Which, in turns, reduces rear lift (increases rear downforce).

When a car has lift or downforce, it usually creates drag. Since a typical car has some lift in its basic design, by adding a spoiler to just remove this lift force, you also reduce drag. When you further increase the spoiler effect, you then create downforce, thus increasing the drag.

When a rear spoiler begins to look more like a wing, then you are in an extreme case of downforce and drag is definitely induced.

So with stationary spoilers, you set them to a position that will give you the best compromise between drag and downforce for your particular application.

If you have active spoilers, then you can adjust them to «low drag» when you want fuel economy or try to reach higher speeds or you can set them to «high downforce» when you want to increase traction & stability. You can also set them to «high drag» when you are slowing down to assist your braking system.

Staff: Mentor

Is there a weight cost to active spoilers?
Is there enough benefit from an active spoiler versus a fixed spoiler to offset that cost?

The benefit is enormous under racing conditions where you really need the downforce in corners but must minimize drag on the straights. In many classes the weight is essentially free because it just reduces the amount of ballast that needs to be added to bring the car up to the minimum weight required by the regulations.

The other problems are mechanical complexity, increased cost, increased danger to spectators and drivers because the speeds are so much higher and because failure of the active device means that the car is suddenly uncontrollable. None of these are high on the priority list of a formula team that wants to win.

The main reason you do not see active aero devices ( spoilers, splitters etc) is the governing rules of the sanctioning organization. Their reasoning is cost cutting as a fixed piece of fiber galss or carbon fiber is cheaper than one with an activating mechanism. In Nascar they really clamp down on any adjustments as a safety consideration. On super speedways they know exactly the aero down force and can limit "safe speed" to a point. In F1 if you give them an inch they will take 2 miles. Just look back to the ridiculous twin wing things that ran in the 1970s. Racing at the local level is sanctioned to keep some kind of cost savings. Regulations limit you to a hard " spec tire" or limit the number of new tires you can race in any one event to cut cost..hahahah..right. In the Saturday night bull rings that week end racer run, you are limited to fixed spoilers at set height, width and in some cases, angles. Material is dictated as well. Clear plastic so drivers following the lead car can see the lead cars driver when he signals signals.
We all know active aero is the hot ticket but its a rules thing.

Formula 1 has modified their position on active spoilers which are now called the "DRS" (Drag reduction system) in which allows part of the spoiler blade to be flattened to reduce the spoiler drag and the racer regulators determine the "DRS zones" of each race course and electronically control where this device can be activated by a driver (as long as his car is within 1 second of the car ahead of his). The drag reduction benefit of these devices for passing can be clearly seen when activated to achieve a pass on the leading car.

As I recall (before DRS) one team experimented with using the drivers knee to block air flowing through a tube. This air was then routed in such a way that it stalled or unstalled the rear wing changing it's drag properties.

If I remember correctly about the time of Senna's death F1 cars had active spoilers and active suspension. There were a number of accidents involving the failure of these components. I remember one were the car, travelling at speed, flew into the air because the active suspension failed and the car defaulted to its maximum height. I believe that it was in part because of Senna's death that these things were banned.

My mitsubishi 3000GT VR4 twin turbo came from the factory moving front and rear spoilers........and a dual mode muffling system so they do exist but the only moving aero I consider useful is in reducing excessive lift as found in the audi TT and VW beetle......etc.....you know....cars that have insane amounts of lift at speed as to be dangerous.

Really, the reasons you don't see moving aero in racing (other than the cheating).

1. They are not legal in most classes.

2. It is hard to maintain the perfect "balance" of front and rear downforce with moving aero.